add a serialiser for xvariant to json

xtensor-stack · Aug 3, 2020 · 5290221 · 5290221
1 parent 24d3c31
commit 5290221
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Showing 2 changed files with 34 additions and 1 deletion.
diff --git a/include/xtl/xjson.hpp b/include/xtl/xjson.hpp
@@ -17,7 +17,7 @@
 
 #include <cstddef>
 #include <string>
-
+#include "xtl/xvariant.hpp"
 #include "nlohmann/json.hpp"
 
 namespace xtl
@@ -82,4 +82,15 @@ namespace xtl
     }
 }
 
+// overloading in the mpark namespace because `xtl::variant` is just a typedef on `mpark::variant`
+namespace mpark
+{
+    template <class... Ts>
+    void to_json(nlohmann::json& j, const xtl::variant<Ts...>& data) {
+        xtl::visit(
+            [&] (const auto & arg) { j = arg; }, data
+        );
+    }
+}
+
 #endif
diff --git a/test/test_xvariant.cpp b/test/test_xvariant.cpp
@@ -15,6 +15,10 @@
 #include "gtest/gtest.h"
 #include "xtl/xtl_config.hpp"
 
+#ifdef HAVE_NLOHMANN_JSON
+#include "xtl/xjson.hpp"
+#endif
+
 using namespace std::literals;
 
 namespace xtl
@@ -203,4 +207,22 @@ namespace xtl
 
         EXPECT_TRUE(res);
     }
+
+#ifdef HAVE_NLOHMANN_JSON
+    TEST(xvariant, json)
+    {
+        typedef xtl::xvariant<double, std::string> stringNumType;
+
+        nlohmann::json j1;
+        stringNumType m1 = "Hello";
+        j1["salutation"] = m1;
+        EXPECT_EQ(j1.at("salutation"), "Hello");
+
+        nlohmann::json j2;
+        stringNumType m2 = 3.0;
+        j2["num"] = m2;
+        EXPECT_EQ(j2.at("num"), 3.0);
+    }
+#endif
+
 }